import java.util.Scanner;


public class Atividade19 {
	public static void main (String args[]){
	int vetor[]= new int[20];
	Scanner digitar = new Scanner(System.in);
	int cont=-1;
	do{
		cont++;
		vetor[cont]=digitar.nextInt();
			
		}while(vetor[cont]!=0 && cont<30);
	int somar=0;
	cont-=1;
	for(int i = cont;i>=0;i--){
		somar += vetor[i]; 
	}
	int media = somar/cont;
	System.out.println(media);
	}
}
